PROJECT SUMMARY Our long term goal is to define the mechanistic roles of store-operated calcium entry (SOCE) in tumor invasion and metastasis. In this research plan we focus on the role of SOCE in the regulation of invadopodium formation, extracellular matrix degradation and melanoma metastasis. Metastasis is responsible for more than 90% of cancer-related death and there are few treatment options available for metastatic cancer. One essential characteristic for metastatic cells is enhanced motility and invasiveness, which helps tumor cells to overcome barriers imposed by basement membrane and surrounding tissues. It is believed that tumor cells use invadopodia to co-ordinate invasion and ECM degradation. Our recent preliminary studies in melanoma support a model whereby SOCE is locally activated to initiate invadopodium formation, ECM degradation and metastasis through a Ca2+-Pyk2-Src pathway. The expected results from Aim1 will define the spatio-temproal organization of SOCE-mediated Ca2+ signals during invadpodium formation and 3D melanoma invasion. Since the intricate organization of Ca2+ in space, time and concentration is the most critical aspect of Ca2+ mobilization that determines the speed, specificity and robustness of Ca2+ signals, and there is virtually no report on the spatio-temporal regulation of Ca2+ signaling during tumor invasion or metastasis, our anticipated results will bring significant insights into Ca2+ mobilization in disseminating melanoma cells. The successful completion of Aim 2 and 3 will define a novel SOCE-Pyk2-Src pathway in melanoma invasion and metastasis and shed new lights on how deregulated SOCE promote melanoma progression. Importantly, we will use novel selective SOCE blocker GSK-7975A to inhibit the invasion and metastasis of human melanoma single cell suspensions directly isolated from patients with metastatic melanoma. The success of the proposed study will provide a proof of concept for targeting SOCE pathway to intervening melanoma metastasis.